This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We developed a new method that uses Hyperpolarized Helium MRI and targeted contrast agent to detect metastatic cancer cells in lungs. We aim to establish the sensitivity and specificity of our method with respect to other clinically available techniques, such as PET and CT scan. We plan on scanning breast tumor bearing mice after they received an injection of our contrast agent LHRH-SPION. We will utilize 10 breast tumor mice that have already been imaged with other modalities (CT and PET) and have shown sign of metastatic cancer cells in lungs. We are requesting 5 days of additional MRI time to complete our pilot project of the title above. With this time we expect to generate the necessary data for a high-profile publication, as well as preliminary data for an R01 application. Below are additional details about the project achievements thus far. According to the American Cancer Society, more than 1.44 million people will be diagnosed with cancer, and more than 560 thousand will die of it this year in the US. The high mortality rate in these patients has been attributed to the development of subclinical occult micrometastasis simultaneously with the more easily diagnosed primary tumor. Thus, the search for these micrometastatic cells is an issue of significant clinical interest. Sensitive non-invasive methods are needed both for early metastatic disease detection and to monitor subsequent treatments. We are focusing our investigation on the MRI detection of specifically targeted pulmonary metastases. Pulmonary metastases are common and most frequently occur with tumors that have rich systemic venous drainage, like renal cancers, bone sarcomas, choriocarcinomas, melanomas, testicular teratomas, and thyroid carcinomas. However most pulmonary metastases arise from common tumors, such as breast, colorectal, prostate, bronchial, head-and-neck, and renal and, of course, lung cancers. Pulmonary metastases are present in 20-54% of all patients who die of cancer, and detection of pulmonary metastases is crucial in the treatment of patients with cancer. Current screening techniques in lungs (fine-needle aspiration (FNA), bronchoscopy, sputum cytology, PET, and CT are invasive and/or lack the sensitivity necessary to detect micrometastases, single disseminated cells, or small tumor cell clusters in lungs.